Potential impact of application of Z0011 derived criteria to omit axillary lymph node dissection in node positive breast cancer patients

Background: The ACOSOG Z0011 trial, a randomized controlled trial among patients with sentinel node positive breast cancer treated with breast conserving therapy, concluded that axillary lymph node dissection (ALND) can be omitted in these patients. However, questions were raised on the general applicability if the results of the Z0011 trial. Therefore, the aim of this study was to assess the practice changing effect of the Z0011 trial by quantifying the proportion of all node positive breast cancer patients who meet the inclusion criteria which are based on the Z0011 trial, thus in whom an ALND could be omitted.
Methods: A multicenter population based study including patients with clinical T1–2N0–1M0 invasive non-metastatic breast cancer, a positive sentinel node or ultrasound guided lymph node biopsy, treated with breast conserving therapy and adjuvant systemic therapy between January 2007 and December 2012.
Results: A total of 11,031 patients had invasive breast cancer including 3051 cases treated with breast conserving therapy and adjuvant systemic therapy. Subsequently, 916 cases with a positive nodal status underwent an ALND of whom 558 cases (60.9%), representing 5.1% of the total breast cancer population, would potentially have fulfilled the Z0011 criteria.
Conclusion: Application of Z0011 based criteria is practice changing in nearly 61% of all node positive patients, which could result in omission of the ALND in a substantial number of patients in the future. Further research has to be performed on the applicability of these conclusions to other categories of breast cancer patients.